how would i know if i had a virus or hacker deleting my media files on my desktop computer

[c=005E2F][i]the other day i checked some media folders on my desktop computer, and there seems to be less picture files in quite a few folders than i thought? just a hundred pictures in 3 folders i checked when i thought there was thousands of pictures in all 3 folders?

this got be anxious as i have ocd and hoard things, including media files...anyway , how would i know if i had a hacker or virus deleting my files? .....or was there probably always just a hundred pictures files in those folders and i just never realized?[/i][/c]